Field of the Invention
The present invention relates to an apparatus for operatively connecting a rotatable cam ring having a cam groove and a member, such as a movable lens frame which is moved along a profile of the cam groove in association with the rotation of the cam ring, in a lens barrel.
Description of Related Art
FIGS. 10 and 11 show a known arrangement of a cam ring and a movable lens frame. In FIGS. 10 and 11, the cam ring 14 has zooming cam grooves 20 and 21 in which association pins (rollers) 17 and 19 of the movable lens frames 16 and 18, respectively, are displaceable in the optical axis direction of a zoom lens. When the cam ring 14 rotates, the movable lens frames 16 and 18 move in the optical axis direction in accordance with the profiles of the zooming cam grooves 20 and 21, so that positions of lenses supported by the associated lens frames 16 and 18 are changed to vary the distance between the lenses to adjust magnification.
The engagement of the association pins(rollers) 17 and 19 into the corresponding cam grooves 20 and 21 is effected as follows.
In FIG. 10, the movable lens frames 16, 18 which are slidably fitted onto a guide rod 12 extending in parallel with the optical axis are fitted in the cam ring 14, so that the cam grooves 20 and 21 are registered with corresponding threaded holes 16a and 18a of lens frames 16 and 18. After that, the screws 17b and 19b, which are inserted in the corresponding rollers 17a and 19a, are screwed into the associated threaded holes 16a and 18a through the cam grooves 20 and 21.
However, the engagement is a troublesome operation which needs a highly skilled operator, and makes automatic assembling thereof difficult. In the course of manual assembly even by a skilled person, screws 17b and 19b tend to fall into the cam ring 14.
Furthermore, the cam grooves 20 and 21 which are in the form of through holes decrease the strength of the cam ring 14. The decrease in strength is more serious when the cam grooves 20 and 21 are long, and when the provision of more than two cam grooves are necessitated, resulting in the need for an additional reinforcing member.